1. Field of the Invention
The present invention relates to a system for controlling a network traffic path, and more particularly to a network traffic controlling system allowing all switches consisting a network to individually determine the best switching path, rather than to determine switching path by a single root switch as the prior art. In addition, the invention relates to a network traffic controlling method using such network traffic controlling system.
2. Description of the Prior Art
As shown in FIG. 1, according to the prior art, a switch network 5 comprises multiple switches 1, 2, 3, 4 connected together and multiple end terminals 1e, 1f, 2e, 2f, 3e, 3f, 4e, 4f connected to each of the switches 1, 2, 3, 4. In this case, for example, personal computers, servers, routers and the like are used as the end terminals 1e, 1f, 2e, 2f, 3e, 3f, 4e, 4f. 
At this time, each of the switches 1, 2, 3, 4 has ports 1a, 1b, 2a, 2b, 3a, 3b, 4a, 4b for connection with the end terminals 1e, 1f, 2e, 2f, 3e, 3f, 4e, 4f and ports 1c, 1d, 2c, 2d, 3c, 3d, 4c, 4d for connection with other switches.
Conventionally, in order to prevent a frame loop in advance, which can occur in frame switching, a particular switch, for example the switch 1 of the whole switches 1, 2, 3, 4 is selected as a root switch. Accordingly, all frame switching paths of the other switches 2, 3, 4 are determined in reference to the switch 1.
However, when the frame switching operations of the switches 2, 3, 4 are determined by the switch 1, i.e., root switch, there occur many inefficient and unreasonable situations.
For example, under circumstances that switching paths of the whole network are built around the switch 1, frames from switch 3 to switch 4 take a far and inefficient route through <switch 3-switch 1-switch 2-switch 4> even though there exists a near path made through the ports 3d, 4d. 
In other words, according to the single root switch based topology of the prior art, it is highly probable that each of the switches 2, 3, 4 cannot use an optimized switching path when switching frames and is forced to use an inefficient flooding path when flooding frames.
For another example, each of the switches 2, 3, 4 is forced to delay a long time for activation of an alternate port so as to prevent a frame loop from occurring, when its primary link is down. As a result, communications between end terminals 2e, 2f, 3e, 3f, 4e, 4f connected to switches 2, 3, 4 are discontinued for a long time.
In other words, according to the root switch based topology of the prior art, when there occurs a failure in a primary port, each of the switches 2, 3, 4 is forced to delay a long time for activation of a alternate port, concerning about an occurrence of a frame loop.
For still another example, when an ill-intentioned user makes a manipulation of illegally setting another specific switch, for example the switch 4 as a false root switch, rather than the legal root switch, i.e., switch 1, the other switches 1, 2, 3 knowing nothing about it switch all traffics around the switch 4. Under such circumstance, if the switch 4 is inferior to the existing switch 1, each of the switches 1, 2, 3 forms the worst topology in an instant.
In addition, under situation that a switching path is determined in reference to the false root switch, i.e., the switch 4, if an ill-intentioned user connects an monitoring tool to the switch 4 and maliciously monitors all frames passing through the switch 4, users using each of the end terminals 1e, 1f, 2e, 2f, 3e, 3f suffer such serious damage that the user's information is leaked to the ill-intentioned user or modified or damaged.
In other words, according to the single root switch based structure of the prior art, the user (each of the switches) cannot efficiently cope with security infringement of a network using a non-authenticated false root switch or similar tool or program.
Further, when a switching path of a whole network is determined in reference to the switch 1, each of the switches 2, 3, 4 cannot use multiple paths leading to the same destination because it is worried about an occurrence of the frame loop. Accordingly, switching path load balancing in the same VLAN cannot be achieved.
In other words, according to the root switch based topology of the prior art, each of the switches 2, 3, 4 cannot use redundant paths when forwarding frames because it is worried about the occurrence of the frame loop.